How to Repot Tomato Seedlings

Repotting seedlings in general is fairly straightforward. Just plop the plant out, put it in a new container, and refill with soil.

But tomato seedlings are unique in that they like to be buried deeply. They have the ability to form new roots along their stems, so they can be repotted up to their lowest set of leaves. A bigger root system means a healthier and more robust plant.

Tomato seedlings are ready to be repotted when they are at least 3 inches tall, and have a couple sets of “true leaves,” the second and subsequent sets of leaves that appear. The first leaves that sprout, cotyledons, are not leaves at all, but embryonic structures from the seed that provide nutrition until the seedling can make its own food.

Start with clean 4-inch pots and pre-moistened potting mix. If several seedlings are growing in the same pot, some people will snip off the extras and keep only the strongest seedling, so as not to disturb the roots during transplant. But if you repot them before they become rootbound, it’s quite easy to separate the seedlings without damaging the roots.

Water your seedlings to loosen up the potting mix and keep the roots moist while you work. If you started your seedlings in newspaper pots, unroll them. The roots should be fairly developed and free.

Separate the seedlings. Always handle them by their leaves, not their delicate stems. If a leaf pulls off, chances are it will grow back. But if the stem snaps, your seedling is done.

Separate the seedling by gently pulling on its leaves and wiggling it away from the potting mix. The roots should release easily. Let the moist potting mix cling to the roots to protect them from drying out.

Fill the new pot with fresh potting mix, and sink in the seedling to its lowest set of leaves. Pat down the mix gently and water.

Keep your newly repotted seedlings out of direct sunlight for a day or two. Tomato plants are especially susceptible to overwatering, so keep the potting mix barely moist at all times. Water deeply to reach the roots at the bottom (or soak from the bottom up), and only water again when the first inch of the mix feels dry.

Tomato plants can be repotted two or three times before they go in the garden. Moving them into larger containers each time keeps them happy and gives their roots room to grow. If you are repotting a second time, you should pinch off the bottom two or four branches and sink the plant even more deeply into the pot to encourage new root growth along the stem.

And all that recycled newspaper you unraveled? You can recycle them one more time by adding them to your compost!

I usually differentiate between seed starting mix (what I fill the newspaper pots with) and potting mix (what I transplant the seedlings into). The latter is amended with compost (or a plant-specific fertilizer of your choice) to feed the seedlings. You can reuse the original mix but should add nutrients to it first.

ChrisDC

…..so there I was minding my own business and about to fry a tomato when I suddenly realised (after slicing it) that it was full of little wriggly things!

Closer investigation revealed that the wriggly things were in fact sprouting seeds. The best I could manage at short notice was a bit of paper napkin and a very small plastic container so I moistened the paper and folded the seeds into it. And so, my fascination with tomato seedlings began.

Anyway, they’ve subsequently been transferred into little seedling trays, so far there must be close to 50 little plants 🙂 It is the highlight of my day to check their progress first thing in the morning and last thing at night.

Thanks so much for this interesting and informative site! I’ve learnt so much already.

I’m glad you have! Enjoy those seedlings, I often marvel at them as well when they’re growing. 🙂

justsaying

so did you get tomatoes from the wriggly things?

Chris Cunynghame

Hmmm…it’s been a while, but yes, I think I did. Our climate is not really ideal for tomatoes. If you took away the roads and buildings you’d be be left with more or less just a stinking swamp. Ever experienced humidity of 96%? I did make an interesting discovery though. The flowers are extremely attractive to the African Carpenter bee. I’ve never seen so many of these gentle giants as when these plants flowered. And giant they are! I measured a dead one on a steel ruler. Covered the best part of 3cm!

justsaying

Well that is fun. I would bet your heat and humidity is why the seeds started to germinate in the tomato. We rarely get humidity that high here in Wisconsin. Thanks for responding to my curiosity.

Can I ask where you live? We have all the seasons. We had snow today and 40 F.

Chris Cunynghame

Yes of course, I’m on the East Coast of South Africa, closest big city would be Durban. It’s 10am. Temperature 22.4 deg C, humidity 72%, which is quite pleasant for a change. Lately it’s been in the mid to high eighties 🙁 I truly envy you your snow. My mom is German and I had the pleasure of living there as a kid, on and off. Do you keep track of your humidity? What’s normal / average in Wisconsin?

justsaying

Today I woke to 46 F and our humidity is 86, and it has been raining here for several days. April ,into May, showers are bringing us back green grass and early blooming flowers. I am waiting for the lilacs to bloom hoping to find some wild mushrooms to enjoy. Its been a relatively mild winter. Our relative humidity can range between 50 and high 80s depending on the season and time of day. I don’t normally track that, but I do notice when it gets high… which I would say is rare. I really notice when the humidity turns into snow and I have to shovel it off my driveway to get out to work in the morning. The blessing is that winter means that I MAY not have to shovel every week and I certainly do not have to mow every week. 🙂

ChrisDC

Thanks for that, always assumed that the colder it got, the less humidity there would be. And I can honestly say I’ve never shoveled so much as one cubic inch of snow – in my life! Do you have a greenhouse or some sort of atrium? What got you interested in tomatoes? Have you had any success with them? Wish I could upload some photos. I have managed to get at least 3 varieties to produce edible fruit. That’s not to say I ate them though….we have monkeys too.

justsaying

I shovel feet of snow most winters (a few inches to a foot or so at a time). It is good exercise. My first tomatoes were gifted plants from heirloom seeds grown by a neighbor. They were wonderful pure organic acidic marvels (varieties were red and yellow jelly beans and a Mortgage lifter) and I saved the seeds to try my hand at growing them again and have since started a little grow project each spring under some shop lights in the basement. It is a great break from the snow shoveling. I am trying a new variety this year. I start a couple dozen of each variety to make sure I have enough and then give away most of them to friends and family once I get them hardened off. I have to fence the garden to protect them from deer and chipmunks.. which I suspect is a lot easier than if I were trying to keep out monkeys.

ChrisDC

As you may have deduced from my first post, I’m more of an ‘accidental’ gardener 🙂 I’ve never bought seeds of any kind although two of my tomato varieties were grown from seeds saved from fruit that was grown from packet seeds planted by a friend. They were both small round cherry varieties, the one being yellow, possibly a Pomodoro of sorts. These plants were attacked by a tunnel borer pest. In spite of the terrible damage inflicted by this pest these plants did bear fruit. I don’t remember if the monkeys were partial to the little fruits. They will steal the bigger tomatoes though, even when they are still green. I’m very fortunate in that I have quite a lot of space so it’s possible to grow hundreds of seedlings at a time. The main problem is the awful heat, it’s dangerous to go outside without a hat (think sunstroke & skin cancer) and the area is badly infested with mosquitoes almost all year long. If it weren’t for that I don’t think I’d ever go inside 🙂

justsaying

It sounds like you have the perfect environment to grow herbs inside. Some are known to repel mosquitoes. I plant basil , lemon balm and catnip by my doors. I am not sure if it works but it makes for a short trip to get basil.

ChrisDC

Part of my survival strategy (I don’t have air-conditioning) is to keep the doors and curtains closed during the day in a bid to keep the house cool. Then at night, open everything up to vent the house. I’ve researched this on the net and this does seem to be standard practice in other countries with similar climates. This results in low light levels though. Everything I’ve grown on window sills tends to become long and straggly, probably because the plants are searching for light. I’ve resigned myself to burning a liquid mosquito repellent 24/7 indoors. I work at home so it’s absolutely necessary unfortunately. Outside I had a lot of lemon grass at one time, which I believe is beneficial in repelling pests. I think you may be right about herbs in general though, growing well here. There is a particular herb that’s gone completely wild, seeding itself everywhere.

justsaying

My rosemary has done poorly here. Likely because it has to stay in a pot year round and come inside for the winter, which is dry and provides less light, even with grow lights. The furnace dries the air inside and we have to use a humidifier. I suspect that if you had a window sill between the shade and the window, that space would fry the plants. It’s too bad that you have that great climate and can’t enjoy it (says the person still recovering from winter).
I also don’t have air conditioning and draw my drapes during the day in the summer and it works well to keep my home comfortable. In the winter I open the drapes first thing in the morning to let the light in and then close them up at dusk to add an insulation barrier to the windows.

ChrisDC

Interesting about your rosemary. My experience shows the plants to be virtually indestructible, I don’t even water mine. I’ll put one in a pot and see how it does. My very first rosemary plant, 4 years on, is (and has been for years) a very substantial bush and is extremely popular with the birds. Just brushing against the plant as you walk by releases the most wonderful smell. I can’t help smiling when I think about how nice the birds must smell after they’ve been in it. As a matter of interest, what do you consider a comfortable temperature? Where do you set the thermostat for your furnace?

justsaying

I understand that I should put my rosemary on a water/rock tray to give it the humidity that it needs to survive the winter inside….I took one downstairs and put it under the light hoping it will survive until I can let it go outside. They really do better here in the summer. It is getting them through the winter here that is the problem. We really only get about 8 hours of light in the midwinter mixed with the dry air, they get pretty homesick, lol. I would venture a guess that your rosemary is living off your humidity (and airborne dust/ nutrients).
I am in zone 3/4 so we have a limited (by many standards) of plants that make it through the winter freeze here. Many of the plants that thrive in southern climates, we grow as annuals.
I set my thermostat at 70F. I like 70s to 80sF and don’t mind higher. We rarely get such high humidity that our heat is “terrible” yet I am one of a few here without air conditioning. I’m just too frugal for the 2 days each summer I wish I had it. Comfortable is relative. You will see WIsconsinites bundle up in the fall when the temps drop into the 50s but when the winter is winding down and we get those first few days of sunshine and 40’s the shorts and short sleeves come out.
Gotta go to work…later?

ChrisDC

I find your posts very interesting, lots of general lifestyle info to be gleaned there. I have pen pals all over the world but none in the US, unless Brazil counts? Those temps are interesting. Your 70 is about as much as I can comfortably bear here. There definitely seems to be a difference generating heat from cold as opposed to cold from heat. The former seems to result in ‘cosy’ whereas the later is uncomfortable. Also, in your case, if it gets too hot, you can always go outside 🙂 Your rosemary continues to baffle me. Example: Annual plant dies, rosemary seeds itself in pot. I don’t notice it, it gets no water and dies, I need pot, throw ‘dead’ rosemary into empty trough, dead rosemary lies there in full sun, for days, roots exposed, then springs back to life! Maybe you’re just being too nice to your plants? When I Googled Wisconsin, I was surprised to see how far north it was. Almost on the same line of latitude as Germany. Looks like a truly beautiful part of the world. The cities have lovely names, Madison for example….

justsaying

I too really enjoy learning from you. I would take our conversation to email if you wish. I woke to 32F with 93% humidity but as the sun burns bright today (and it will be a beautiful sunny day here today) we are predicted to get to 74 F (22 C) and the humidity will be down below 40%. It got nice enough yesterday that I was able to open my windows and get some fresh air into my house- Wooo hooo. Tonight they are warning that some of the tender (not native to this climate) plants that came up with the warm days, may suffer frost damage as the temps go back down near freezing again…then we will be back up to 60F by the afternoon. That is pretty typical spring here as our sun angle changes.
I have heard that we are too nice to rosemary, as far a winter watering, yet it needs that high humidity and I just can’t take my house above 55% or so humidity in the winter without harming my house. The condensation on the windows (from the temperature difference between the inside/70 and outside/often below 0 F) would cause mold to grow in the window sills and that will start all kinds of trouble. We humidify homes in the winter to about 55% ..a fine line between saving our skin and wood furniture, etc. from “too dry” and having moisture problems start in the home.
Rosemary takes up to 3 weeks to germinate, and the one time I tried it, I used a heat mat under the seeds, then bright light and moisture/ humidity.. and it only lived to about 2″ tall before I just couldn’t provide the conditions to sustain it. I decided that was a waste of a month of my life and I would just buy established plants and try to keep them alive all year. I have one that is doing well (grow lights in the basement) and one that was in my south facing window that was dying so is now also under the grow lights. I hope they both make it the last 4 weeks of “winter” here… Our last usual day of frost risk is the end of May, so that is when we plan prep our gardens and plant seeds or transplant our seedlings outside. Some plants have to wait until the soil warms into the 50s F, which can take another couple weeks.
I will be off line until Sunday, because I will be visiting / helping my elderly mother. Have a great weekend and if you wish, give me your email address and we can leave this poor site some relief from us.

ChrisDC

Thanks, yes we can certainly email direct. I’ve kinda been expecting Linda to pull the plug on our little tête-à-tête – we have wandered rather far off topic. Nevertheless, I get the feeling our Garden Betty is a very savvy lady, and like the good gardener she is, would probably transplant us to a more appropriate spot:). Maybe this site could use a ‘What did you do in your garden today?’ section / thread. No doubt it will help stimulate interesting discussions beneficial to both Linda and the public. Linda, what do you say? Can we ramble on right here? My name is Chris and I can be emailed direct on chrisdc_pandora@hotmail.com

I think it’s awesome you two resurrected an old comment thread and have been chatting it up these past couple of weeks! The community of people here is what makes the blog so fun and rewarding for me. And I especially love the fact that one person in Wisconsin can connect with another all the way in South Africa — two different cultures and climate zones, bonding over a shared interest!

justsaying

Thank you for being so gracious and tolerant of my curiosity. I love it too. Thanks.

Rhi

Hi, I need to transplant my tomato seedlings into bigger pots because right now I have multiple growing in very little pots. For me space is an issue because I’m growing everything in containers on my back porch (no ground garden unfortunately). Can I transplant multiple seedlings into a bigger pot and then transplant them again to each have their own container once they’re big enough? If so, how far apart should I plant them in one container? A few inches?
Thanks for the help!

Ian- It only sounds “fiddly” if you’ve never raised and planted tomatoes before… it’s simply how it’s done. If you skipped transplanting them, you’d have weak, worthless plants on your hands. If ever you buy tomato seedlings from a garden center, you want short and stalky plants… never tall and spindly. The shorter ones are healthier and have the strong root systems you want, which occurs when you transplant your seedlings in the manner described. You also want to plant them to within an inch of their lowest leaves when you put them in their permanent homes in the ground or in large containers outside, too–they will continue growing stronger and stronger roots if planted that way. (FYI- my tomatoes were the healthiest ever last year… no black-winged aphids at all, and all I did differently was interplant basil with them and use old coffee grounds as a fertilizer.)

Companion planting is clever stuff isn’t it? This is the stuff that our grandfathers took for granted. Seems like the old ways are still the best when it comes to gardening. Nothing like the pressure of actually going hungry to motivate you to get it right eh?
Re the toms, yes I see that now, now I know why I felt like I ran out of time with my first toms last year. Weak roots that took way too long to get established.
You’ve saved the day here 🙂
Thanks!

Chris Cunynghame

Julia, if you’re still out there… Your reference to old coffee grounds interests me greatly. I generate about 1 liter by volume of grounds every week. After a friend told me it’s not a good idea to pour them down the drain (goes to septic tank) I started pouring them out into the garden – always the same place because I burn twigs and small branches on that spot. I noticed the grass seems to grow particularly well in this area. Could you elaborate on how much you use and how often?

The reason for re-potting is to keep burying the stems deeper each time, and thereby encouraging more roots to develop along the part of the stem that’s underground. Planting your tomatoes in a gallon pot initially would make no difference than if you were to plant them in a smaller pot, other than giving you more time to plant them outside before they get rootbound.

I have to tomato seedlings in one pot. I’m planning to remove the smaller one to the other pot so they can both survive. What is the best way to separate them from one another? My friend told me to take the soil ball and irrigate it until the soil disappear. Then untangle them gently. I’m planning to do it on my tomatoes but can I also use that procedure to my new Marigolds? Thanks!

I just gently pull the roots apart with my hands; never had a problem with any of my seedlings this way.

oukay

I found that I would put off the transplanting too long if I put them in new pots. so now I start my tomatoes in cups or 4″ pots with just a couple of inches of soil. Then as they get larger I start adding soil to progressively cover the stem. This works well for me.

Very interesting viewpoint. I have always waited until the true leaves appeared before transplanting. This way the seedlings can draw more energy from a larger source than the cotyledons, thus increasing their chances of survival. All my plants have done well this way. But I agree that the sooner and smaller the plant, the better.

I’d recommend transplanting them at an earlier stage. About a week or 10 days before the ones shown. An earlier stage reduces transplant shock which slows growth and could effect primordial floral development.

Love the post. For seed germination, we use the cores to toilet paper rolls and cut them in half and get two from each core. Works great and, as you point out, excellent for compost once plants are transplanted.

AshleyWaterstradt

Thank you so much for all of this great information! This is my first time growing from seeds, and I’m loving all of your posts. 🙂

Thanks for sharing the knowledge about repot of tomato seeding. This knowledge helps me so much in future.
I am here for first time and likes the blog entries in this blog.I will glad to follow this blog in future

With regards
Shaun…….

Hello!

I’m Linda and I’m the Garden Betty. I like to grow my own food and celebrate life around good meals. I love to turn weekend getaways into week-long road trips and spend my days in the sun, sand or surf. Read more